AGRO 88 |
| An ambient air monitoring program conducted in central Washington State in the fall of 2005 established that gaseous methyl isothiocyanate (MITC) emissions approached or exceeded California EPA Reference Exposure Level and/or EPA Office of Pesticide Protection (OPP) criteria for acute and sub-chronic residential inhalation exposure. To minimize residential exposure, a near-field air monitoring program was conducted in this region in the fall of 2006 that examined off-target MITC movement from center pivot chemigation and soil-incorporated shank injection with compaction. A low pressure center pivot system was used to apply Sectagon 42® (42% metam sodium) to a 33 acre circle in October. An adjacent 119 acre crop circle with near-identical soil characteristics was treated with a similar application rate of Sectagon 42® by shank injection ca. 3 weeks later in early November. Near-field MITC emissions were monitored at eight air sampling stations surrounding each circle before, during, and up to 4 days after fumigation. A maximum field averaged concentration of 224 µg/m3 was observed during the chemigation event; whereas, a 10 fold reduction field averaged concentration of 22.5 µg/m3 was observed by shank injection during the same field fumigation period. For the center pivot application, a maximum downwind MITC concentration of 987 µg/m3 was observed in comparison to a maximum downwind shank injection concentration of 141 µg/m3. This study lends support for the use of shank injection for minimizing off-target fumigant emissions on fields in close proximity to residential communities in central Washington State. |
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Investigating VOCs from Pesticide and Fumigant Applications: State of the Science and New Approaches to Protect Air Quality
1:45 PM-5:10 PM, Monday, August 20, 2007 BCEC -- 259 A/B, Oral
Division of Agrochemicals |